Stereoscopic television system

ABSTRACT

A stereoscopic television system employs a plurality of camera units each having an optical system and an image pickup element to photograph and display images of an object. The displayed images are processed with a stereoscopic image processor to provide stereoscopic images. The system comprises detectors for receiving image signals based on the images photogaphed by the camera units and correlatively comparing the image signals with each other to detect deviations of the images photographed by the camera units and provide image deviation signals; and correcting devices for correcting the deviations of the images according to the image deviation signals provided by the detectors.

This application is a division of application Ser. No. 07/397,958, filedAug. 23, 1989, now U.S. Pat. No. 5,003,385.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stereoscopic television system thatcan prevent the optical axes of a plurality of camera units disposed inthe television system from deviating from their correct paths and thusprovide stereoscopic images of an object.

2. Description of the Prior Art

Some work sites, such as the deep sea and space, are hardly accessibleby worker, or some work sites such as nuclear reactors may risk thesafety of workers. To work in a hazardous environment or at suchinaccessible sites, a manipulator is useful. The manipulator is remotelycontrolled by operators who are positioned at a safe distance far fromthe work site.

According to this technique, the image of the work site (workenvironment) is taken by camera units, and images of the work site arestereoscopically displayed on a display units such as a monitortelevision unit. Viewing the images on the display unit, the operatorremotely controls the manipulator.

FIG. 1 is a view showing a conventional stereoscopic television systemfor providing stereoscopic images of a work site for the purpose ofremote control.

The stereoscopic television system of FIG. 1 comprises a right cameraunit 101a, a left camera unit 101b, an image mixer 102, a frameconverter 103, a shutter-spectacles driver 104, shutter-spectacles 105,and a monitor television unit 106. The two camera units 101a and 101bare horizontally arranged side by side on a universal head (not shown)to simultaneously photograph a front object 107. The camera units 101aand 101b are provided with optical systems 101c and 101d, respectively.Each optical system generally comprises a zoom lens.

Light from the object 107 passes through the optical systems 101c and101d to form images on image pickup elements (not shown) of the cameraunits 101a and 101b. Then, the image pickup elements send video signalsto the image mixer 102, from which the video signals are alternatelyoutputted at predetermined intervals to the frame converter 103. Theframe converter 103 carries out a flickerless process on the videosignals to remove flicker from the images. Then, the video signals arealternately provided for the monitor television unit 106.

A viewer 108 senses stereoscopic images from the images displayed on themonitor television unit 106 through the shutter spectacles 105 whoseleft and right spectacles are alternately opened and closed according tosynchronous signals provided by the frame converter 103. Namely, thestereoscopic television system of this arrangement utilizes theafterimages in human eyes to provide the sense of stereoscopic images.

When the viewer 108 wants to have an image of wide-view angle ortele-view-angle through the zoom lenses of the optical systems 101c and101d, the viewer 108 may operate a lens controller 109. If the operatorwants to adjust a distance between the camera units 101a and 101b or aviewing angle of the object 107, the viewer 108 may operate a universalhead controller 110.

To let the viewer 108 sense stereoscopic images from the stereoscopictelevision system of such an arrangement, it is necessary to align theimages projected on the left and right eyes of the viewer 108 with eachother in the magnifications, positions, postures, etc., of the images.To do so, optical axes of the optical systems 101c and 101d extending tothe image pickup elements (not shown) are set in a plane that includesthe camera units 101a and 101b.

When the optical systems 101c and 101d comprise zoom lenses, the opticalaxes of the zoom lenses are stationary even if their zoomingmagnifications are changed. To realize this, the lenses shall becarefully selected and precisely positioned. In practice however, it isvery difficult to prepare lenses of equal properties and to strictlymaintain their setting positions under external influences.

Namely, if the conventional stereoscopic television system employs zoomlenses for its optical systems 101c and 101d, the optical axes of thelenses tend to deviate from their correct paths. Particularly when thezoom lenses are operated to zooming positions, the optical axes maygreatly deviate from their correct paths. Then, images projected on theleft and right eyes of the viewer 108 will not align with each other,and the viewer cannot correctly sense stereoscopic images.

When the stereoscopic television system is used in hazardous environmentto remotely control a manipulator and if the system causes suchdeviations on its optical axes, the observer cannot conceive goodstereoscopic images of an object to be handled by the manipulator. Thiswill deteriorate the safety of the work and the operability of themanipulator.

As described above, a the conventional stereoscopic television systemcomprises a plurality of the camera units 101a and 101b provided withthe optical systems 101c and 101d. To align optical axes of the opticalsystems with their proper paths, the optical systems shall use lenses ofequal properties, precisely assembled in the optical systems 101c and101d. When the lenses are zoom lenses, optical axes of the opticalsystems 101c and 101d tend to deviate from the proper paths in takingzooming positions. Then, proper stereoscopic images are not adequatelyprovided.

SUMMARY OF THE INVENTION

To solve the above-mentioned problems an object of the present inventionis to provide a stereoscopic television system comprising a plurality ofcamera units for providing stereoscopic images, which can prevent theoptical axes of the optical systems in the camera units from deviatingfrom their correct paths, thus preventing the images from deviating fromeach other and providing proper stereoscopic images.

According to an aspect of the invention, a stereoscopic televisionsystem comprises a plurality of camera units each having an opticalsystem and an image pickup element. Images of an object are photographedby the camera units and displayed. The images are processed with astereoscopic image processing means, to provide stereoscopic images to aviewer.

Each of the camera units further comprises a first beam splitterdisposed between the optical system and the image pickup element, asecond beam splitter disposed on the object side of the optical system,a light source for emitting a reference beam to the first beam splitter,and a light receiving element. The reference beam emitted from the lightsource is reflected by the first beam splitter, passed through theoptical system, reflected by the second beam splitter, and received bythe light receiving element.

The stereoscopic television system further comprises arithmetic meansfor operating an optical axis deviation of each optical system accordingto the reference beam received by the light receiving element, andcorrecting means for correcting the deviation of the optical systemaccording to the information provided by the arithmetic means.

The reference beam emitted from the light source is reflected by thefirst beam splitter located on the image pickup element side, passedthrough the optical system, reflected by the second beam splitterlocated on the object side, and guided to the light receiving element.If the optical axis of the optical system deviates from its correctpath, the reference beam is affected by the deviation, and, therefore,an incidental position of the reference beam on a light receiving faceof the light receiving element deviates from a normal incidentalposition. The deviation of the incidental position of the reference beamis operated, and, based on a result of the operation, the deviation ofthe optical axis of the optical system is corrected.

According to another aspect of the invention, a stereoscopic televisionsystem alternately displays right and left input images and processesthe images to provide stereoscopic images to a viewer. The systemcomprises first polarizing means for polarizing right image light toform first-type polarized light, second polarization means forpolarizing left image light to form second-type polarized light, meansfor putting the first-type and second-type polarized light on a commonoptical axis and supplying the light to a single optical system,polarization switching means for alternately passing the first-typepolarized light and second-type polarized light with the common opticalaxis, means for displaying images based on the polarized light, andmeans for processing the images to provide stereoscopic images.

These and other objects, features and advantages of the presentinvention will be more apparent from the following detailed descriptionof preferred embodiments in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a stereoscopic television systemprior art;

FIG. 2 is a schematic view showing a stereoscopic television systemaccording to a first embodiment of the present invention;

FIG. 3 is a schematic view showing certain essential parts of themodification of the embodiment shown in FIG. 2;

FIG. 4 is a schematic view showing a stereoscopic television systemaccording to a second embodiment of the invention;

FIG. 5 is a schematic view showing a stereoscopic television systemaccording to a third embodiment of the invention; and

FIG. 6 is a schematic view showing a modification of the embodimentshown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a schematic view showing a stereoscopic television systemaccording to the first embodiment of the invention. Two camera units 1aand 1b corresponding to right and left views, respectively, arehorizontally arranged side by side on a universal head (not shown). Thecamera units 1a and 1b are spaced apart from each other by apredetermined distance to photograph an object A.

The camera units 1a and 1b are moved horizontally and vertically bymeans of moving mechanisms 2a and 2b, respectively. The movingmechanisms 2a and 2b are disposed on the universal head (not shown) andeach comprises an actuator, such as a piezoelectric element.

The camera units 1a and 1b further comprises optical systems,respectively. The optical systems comprise zoom lenses 3a and 3b andimage pickup elements 4a and 4b, respectively. The image pickup elements4a and 4b may be CCDs, etc.

Image information integrators 5a and 5b receive image signals 6a and 6bfrom the image pickup elements 4a and 4b, and integrate horizontalbrightness (quantities of light) of the images of the object A tocompress the information. Namely, the integrators 5a and 5b converttwo-dimensional distribution of light quantities into one-dimensionalvertical distribution of the light quantities.

A relative deviation operating unit 8 correlatively compares imageinformation signals 7a and 7b outputted from the image informationintegrators 5a and 5b with each other to numerically operate thevertical deviations of the right and left images photographed by thecamera units 1a and 1b to quantitatively detect the deviations of theimages.

Namely, if the zoom lenses 3a and 3b of the camera units 1a and 1b causetheir optical axes to deviate from their proper paths, or if zoomingoperations of the lenses 3a and 3b cause their magnifications to deviatefrom correct magnifications, the image signals 6a and 6b from the imagepickup elements 4a and 4b may be affected by the deviation and thenreceived by the image information integrators 5a and 5b. Therefore, aresult of the operation carried out in the relative deviation operatingunit 8 corresponds to the optical axis deviation or magnificationdeviation of the zoom lenses 3a and 3b.

In this way, the image information integrators 5a and 5b and relativedeviation operating unit 8 constitutes a detecting means for detectingdeviations of images taken by the camera units 1a and 1b.

The relative deviation operating unit 8A outputs a relative deviationsignal 10 to a correction signal generator 9, which provides correctionsignals 11a and 11b for correcting the deviation of the imagesphotographed by the camera units 1a and 1b. The correction signals 11aand 11b are provided for the moving mechanisms 2a and 2b of the cameraunits 1a and 1b to correct the deviation of the right and left images.

In this way, the correction signal generator 9 and moving mechanisms 2aand 2b constitute correcting means for correcting the deviation ofimages photographed by the camera units 1a and 1b.

The integrators 5a and 5b, relative deviation operating unit 8 andcorrection signal generator 9 may be constituted by a singlemicrocomputer that realizes the above-mentioned functions, or they maybe realized by exclusive-use circuits, respectively.

An image mixer 12 receives the right and left image signals 6a and 6bfrom the image pickup elements 4a and 4b, and alternately provides thesignals at predetermined intervals to a frame converter 13, from whichthe signals are given to a display unit 14 such as a monitor televisionunit. The frame converter 13 carries out a flickerless process on theimage signals 6a and 6b to provide flickerless images to the observer.

Shutter spectacles 15 are put over the eyes of a viewer 16. Thespectacles 15 receive synchronous signals from the frame converter 13. Aspectacles driver 17 optically and electrically opens and closes rightand left eyes of the shutter spectacles alternately. With the shutterspectacles 15, the viewer 16 can sense images on the display unit 14 asstereoscopic images.

Operation of the stereoscopic television system according to the firstembodiment of the invention will be explained.

The camera units 1a and 1b are set toward the object A. Outside light 1₁and 1₂ from the object A pass through the zoom lenses 3a and 3b, to formimages on the image pickup elements 4a and 4b, respectively. The imagepickup elements 4a and 4b provide image signals 6a and 6b of the objectA to the display unit 14 alternately at predetermined intervals (forexample, every 1/60 seconds) via the image mixer 12 and frame converter13. Then, the viewer 16 observes images that are alternately displayedon the display unit 14 through the shutter spectacles 15 as stereoscopicimages of the object A.

If optical axes are oriented correctly and zooming magnifications in thezoom lenses 3a and 3b are correct, it will be judged that there is nodeviation in the images photographed by the right and left camera units1a and 1b. This judgment is formed according to a result of theoperation carried out in the relative deviation connecting unit 8.Therefore, the moving mechanisms 2a and 2b for correcting deviations ofthe images photographed by the camera units 1a and 1b are not driven.

When a lens controller (not shown) is operated during the photographingoperation of the camera units 1a and 1b to change the zoom lenses 3a and3b from wide angle positions to zooming positions, or when a universalhead controller (not shown) is operated to change an observingdirection, a deviation may occur in, for example, an optical axis of thezoom lens 3a of the camera unit 1a.

If such a deviation occurs, the image signals 6a and 6b from the imagepickup elements 4a and 4b are inputted to the image informationintegrators 5a and 5b. The image information integrators 5a and 5bconvert the image signals 6 and 6b to form one-dimensional verticaldistribution of light quantities, and provides resultant imageinformation signals 7a and 7b to the relative deviation operating unit8.

The relative deviation operating unit 8 correlatively compares the imageinformation signals 7a and 7b with each other to numerically operate avertical deviation of the images photographed by the camera units 1a and1b. Namely, the unit 8 detects relative deviation of the right and leftimages photographed by the camera units 1a and 1b, i.e., a relativevertical deviation of the optical axes of the zoom lenses 3a and 3b.Then, the relative deviation operating unit 8 provides the relativedeviation signal 10 to the correction signal generator 9.

According to the relative deviation signal 10, the correction signalgenerator 9 outputs the correction signals 11a and 11b to the movingmechanisms 2a and 2b of the camera units 1a and 1b.

The moving mechanism 2a is driven according to the correction signal 11ato correct the deviation of the optical axis of the zoom lens 3a thatmoves integrally with the camera unit 1a. Then, the relative deviationoperating unit 8 judges if an image photographed by the camera unit 1bhas no deviation, i.e., there is no deviation in the optical axis of thezoom lens 3b. Therefore, the correction signal generator 9 provides acorrection signal of zero correction to the moving mechanism 2b, whichis therefore not driven.

In this way, even if the optical axes of the zoom lenses 3a and 3bdeviate from their proper paths to deviate images from their correctpositions during the photographing operation of the camera units 1a and1b, the deviation of the optical axes can automatically be corrected sothat the viewer 16 can always sense proper stereoscopic images.

When the stereoscopic television system of the invention is used forremotely controlling a manipulator placed in extreme environment,deviations of the optical axes of the zoom lenses 3a and 3b of thecamera units 1a and 1b, if any, are automatically corrected. Therefore,a viewer of the system can always sense proper stereoscopic images of anobject to improve work safety and the operability of the manipulator.

In addition, the image information integrators 5a and 5b and relativedeviation operating unit 8 detect deviations of images photographed bythe camera units 1a and 1b. Accordingly, the detecting apparatuses arenot affected by environmental conditions under which the camera units 1aand 1b are placed. Therefore, weather resistance against the criticalconditions can be secured with no deterioration of the quality of imagesand no complications or specialization of the camera units 1a and 1b.

In the first embodiment, pieces of image information inputted by thecamera units 1a and 1b are converted by the image informationintegrators 5a and 5b into a one-dimensional distribution of lightquantities of only one direction, i.e., vertical direction tocorrelatively compare the quantities with each other. However, thepieces of input image information may one-dimensionally and spatially beintegrated in vertical, horizontal and oblique directions, By this, therotations or horizontal deviations of images may quickly and accuratelybe corrected.

According to the embodiment, the correlational comparison is doneaccording to the converted one-dimensional distribution of quantities oflight. Instead, pieces of image information may be correlativelycompared with each other according to color tone. Further, the pieces ofimage information may be correlatively compared with each otheraccording to the distribution of light quantities and the distributionof color tones.

In the embodiment, the relative deviation operating unit 8 calculates adeviation of image by correlatively comparing pieces of theone-dimensionally compressed image information with each other. Theimage deviation may be calculated according to mean error quantities ofthe pieces of one-dimensionally compressed image information.

Although the embodiment has been explained for the case where theoptical axis of the zoom lens 3a of the camera unit 1a has deviated fromits correct path, deviations of the optical axes of both the zoom lenses3a and 3b may be corrected in the similar manner. Even if one or both ofthe camera units 1a and 1b are subjected to shocks, to cause deviationsof images from their correct positions, the deviations can easily becorrected.

The embodiment employs zoom lenses as optical systems. It is possible toemploy single-focus lenses as optical systems.

To correct deviations of the optical axes of the zoom lenses 3a and 3bin the first embodiment, the correction signal generator 9 outputs thecorrection signals 11a and 11b to drive the moving mechanisms 2a and 2bto mechanically correct the deviations of the optical axes. Instead, itis possible to correct the deviations of the optical axes byelectrically moving images displayed on the display unit 14.

FIG. 3 is a schematic view showing essential part of a stereoscopictelevision system according to a modification of the first embodiment.According to the modification, image pickup elements 4a and 4b provideimage signals 6a and 6b to small monitor television units 18a and 18bsuch as electronic view finders, etc., to display right and left imagesphotographed by camera units 1a and 1b on the monitor units 18a and 18b,respectively. The two images are one-dimensionally integrated by twocylindrical lenses 19a and 19b to form images on linear CCDs 20a and20b, respectively.

According to the modification, the cylindrical lenses 19a and 19bconvert images photographed by the camera units 1a and 1b intoone-dimensional vertical distributions of light quantities to provideimage information signals 7a and 7b to a relative deviation operatingunit 8. Other arrangements of the modification are the same as those ofthe first embodiment.

To provide one-dimensional images in plural directions by thismodification, a plurality of cylindrical lenses may be arrangedvertically, horizontally and obliquely.

Although the modification has employed the cylindrical lenses tooptically and one-dimensionally integrate images, spherical lenses maybe employed instead of the cylindrical lenses to realize two-dimensionaloptical integration. In this case, images are converted intodistribution patterns of light spots.

The first embodiment and its modification explained in the above havespatially integrated pieces of image information inputted from thecamera units 1a and 1b and correlatively compared them with each other.It is possible to employ high-speed operational elements tocorrelatively compare all pixels of image information inputted from thecamera units 1a and 1b with each other.

As described in the above in detail, according to the first embodimentof the invention, deviations of images photographed by camera units thatmay be caused by deviations of optical axes of optical systems of thecamera units can automatically be corrected. Therefore, a display unitcan provide good images from which a viewer can always sense properstereoscopic images.

FIG. 4 shows a stereoscopic television system according to the secondembodiment of the invention.

In FIG. 4, two camera units 18a and 18b are horizontally arranged sideby side with a predetermined space between them on a universal head (notshown) to photograph an object A from the right-hand side and from theleft-hand side. The camera units 18a and 18b are horizontally andvertically moved by moving mechanisms 2a and 2b, respectively. Themoving mechanisms 2a and 2b are disposed on the universal head (notshown) and comprise actuators such as piezoelectric elements.

Each of the camera units 18a and 18b comprises an optical system, i.e.,a zoom lens 20, an image pickup element 21 such as a CCD, a first beamsplitter 22 disposed between the optical system 20 and the image pickupelement 21, a second beam splitter 23 disposed on the object A side ofthe zoom lens 20, a light source fitted to the side face of the firstbeam splitter 22, a light receiving element 25 fitted to the side faceof the second beam splitter 23, and an optical path correcting opticalsystem 26 disposed between the image pickup element 21 and the firstbeam splitter 22 to correct the total length of an optical path of thebeam splitter 22.

Each of the first and second beam splitters 22 and 23 comprises a halfmirror. The light source 24 is a spot light source for emitting a lightbeam such as a laser light beam. The light receiving element 25comprises a PSD (Position Sensing Device) such as a CCD that can readcoordinates of a received light beam.

A reference beam (for example, a laser beam) 1₁ emitted from the lightsource 24 is reflected by the first beam splitter 22, passed through thezoom lens 20, reflected by the second beam splitter 23, and madeincident to the light receiving element 25. Here, the reference beam 1₁from the light source 24 is read for its coordinates by the lightreceiving element 25.

If an optical axis of the zoom lens 20 of any of the camera units 18aand 18b deviates from its correct path, the reference beam 1₁ advancingtoward the second beam splitter 23 is affected by the deviation.Accordingly, an incidental position of the reference beam 1₁ on thelight receiving face of the light receiving element 25 is changedaccording to the deviation of the optical axis of the zoom lens 20. Fromcoordinates of the incidental position of the reference beam 1₁ on thelight receiving element 25, the deviation and direction of the opticalaxis of the zoom lens 20 can be detected.

Optical axis deviation operating units 28a and 28b receive detectivesignals 27a and 27b outputted from the light receiving elements 25 tooperate deviations from previously stored reference positions (positionswhere no deviation is observed on the optical axis of each zoom lens 20)and provide deviation signals 29a and 29b to a relative deviationoperating unit 30.

Based on the deviation signals 29a and 29b outputted from the opticalaxis deviation operating units 28a and 28b, the relative deviationoperating unit 30 operates a relative deviation of the optical axes ofthe zoom lenses 20 of the camera units 18a and 18b to provide a relativedeviation signal 31 to a correction signal generator 32.

In this way, the optical axis deviation operating units 28a and 28b andrelative deviation operating unit 30 constitute arithmetic means foroperating optical axis deviations of the zoom lenses 20.

The correction signal generator 32 receives the relative deviationsignal 31 outputted from the relative deviation operating unit 30 andprovides correction signals 33a an 33b for correcting the deviations ofthe optical axes of the zoom lenses 20, to the moving mechanisms 2a and2b of the camera units 18a and 18b, thus correcting deviations of theoptical axes of the zoom lenses 20.

In this way, the correction signal generator 32 and moving mechanisms 2aand 2b constitute correcting means for correcting deviations of theoptical axes of the zoom lenses 20.

The optical axis deviation operating units 28a and 28b, relativedeviation operating unit 30 and correction signal generator 32 may beformed by a single microcomputer to realize the above-mentionedfunctions, or they may be realized by exclusive-use circuits,respectively.

An image mixer 12 receives image signals 6a and 6b from the image pickupelements 21 to alternately output them at predetermined intervals to aframe converter 13, from which the signals are sent to a display unit 14such as a monitor television unit. The frame converter 13 performs aflickerless process to remove flicker from images.

Shutter spectacles 15 are put over the eyes of a viewer 16. According tosynchronous signals sent from the frame converter 13, a spectaclesdriver 17 electrically opens and closes the left and right spectacles 15alternately. With the spectacles 15, the viewer 16 can sense images onthe display unit 14 as stereoscopic images.

Operation of the stereoscopic television system of the second embodimentof the invention will be explained.

The camera units 18a and 18b are set to face the object A. Outside lightbeams 12 and 13 from the object A are each passed through the secondbeam splitter 23, zoom lens 20, first beam splitter 22 and optical pathcorrecting optical system 26 to form an image on the image pickupelement 21. The image pickup element 21 provides an image signal 6a, 6bof the photographed object A.

The image signals 6a and 6b are passed through the image mixer 12 andthe frame converter 13 and outputted alternately at predeterminedintervals (for example, every 1/60 seconds) to the display unit 14.Then, the viewer 16 uses the shutter spectacles 15 to sense stereoscopicimages of the object A from the images alternately displayed on thedisplay unit 14.

If an optical axis of each of the zoom lenses 20 of the camera units 18aand 18b is correctly oriented, a reference beam 1₁ emitted from thelight source 24 is reflected by the first beam splitter 22, passedthrough the zoom lens 20 and reflected by the second beam splitter 23 toreach a correct point on the light receiving element 25.

Since the reference beam 1₁ is totally reflected by the first beamsplitter 22, the reference beam never influences the image pickupelement 21. Since the incidental point of the reference beam 1₁ on thelight receiving face of the light receiving element 25 such as a PSD isnot changed due to the fact that there is no deviation, the optical axisdeviation operating units 28a and 28b judge that there is no deviationin the optical axes of the zoom lenses 20 so that the moving mechanisms2a and 2b for correcting the optical axes of the camera units 18a and18b are not driven.

While the camera units 18a and 18b are photographing the object A, alens controller (not shown) may be used to change the zoom lenses 20from wide angle positions to zooming positions, or a universal headcontroller (not shown) may be controlled to change the observing angles.At such time, the optical axis of, for example, the zoom lens 20 of thecamera unit 18a may deviate from its correct path. Then, the referencebeam 1₁ emitted from the light source 24 is affected by the deviationwhen the reference beam reflected by the first beam splitter 22 passesthrough the zoom lens 20. Namely, if the optical axis of the zoom lens20 deviates from its correct path, the outside light beam 1₂ from theobject A is also deviated from its correct path in forming an image onthe image pickup element 21.

Therefore, the reference beam 1₁ running from the image pickup element21 toward the object A also deviates from the correct path and thenenters the light receiving face of the light receiving element 25. Thelight receiving element 25 quantitatively reads coordinates of theincidental reference beam and direction of the deviation. Then, thelight receiving element 25 outputs a detective signal 27a to the opticalaxis deviation operating unit 28a.

On the other hand, a light receiving element (not shown) of the cameraunit 18b whose optical axis does not deviate from its correct pathprovides a detective signal 27b of no deviation to the optical axisdeviation operating unit 28b.

The optical axis deviation operating apparatuses 28a and 28b receive thedetective signals 27a and 27b, and operates deviations based onreference positions (where no deviation occurs on the optical axes ofthe zoom lenses 3) to output resultant signals 29a and 29b to therelative deviation operating unit 30.

Based on the deviation signals 29a and 29b, the relative deviationoperating on unit 30 operates relative deviations of the reference beams1₁ that have been made incident to the light receiving faces of thelight receiving elements 25 of the camera units 18a and 18b. Namely, arelative deviation of the optical axes of the zoom lenses 20 iscalculated. Results of the operation are outputted to the correctionsignal generator 32.

According to the relative deviation signal 31, the correction signalgenerator 32 outputs correction signals 33a and 33b to the movingmechanisms 2a and 2b of the camera units 18a and 18b.

At this time, a zoom lens (not shown) of the camera unit 18b has nodeviation in its optical axis. Namely, the incidental position of thereference beam to the light receiving element has no deviation from thecorrect position. Therefore, the optical axis deviation operating system28b judges that the optical axis of the zoom lens (not shown) of thecamera unit 18b has no deviation from the correct position. As a result,the correction signal generator 32 outputs the correction signal 33b ofzero correction to the moving mechanism 2b not to drive the movingmechanism 2b.

On the other hand, the moving mechanism 2b is driven according to thecorrection signal 33a to correct the optical axis of the zoom lens 20that moves integrally with the camera unit 18a.

In this way, while the camera units 18a and 18b are photographing objectA, deviations, if any, of the optical axes of the zoom lenses 20 fromtheir correct paths are automatically corrected so that the viewer 16can always sense proper stereoscopic images.

When the stereoscopic television system of the second embodiment isemployed to remotely control a manipulator in a severe environment, anydeviations of the optical axes of the zoom lenses 20 of the camera units18a and 18b from their correct paths are automatically corrected so thatthe viewer can always sense proper stereoscopic images of an object. Asa result, the safety of work and the operability of the manipulator areimproved.

The first and second beam splitters 22 and 23, light source 24 and lightreceiving element 25 constitute means for detecting the deviation of anoptical axis of each zoom lens 20 and are integrally disposed with thezoom lens 20 and image pickup element 21 in the camera unit 18a, 18b) sothat the system of the second embodiment has weather resistance in asevere environment.

Although the second embodiment has been explained for the case thatoptical axis deviation has occurred on the zoom lens 20 of the cameraunit 18a, the embodiment can correct deviations occurring on opticalaxes of both the zoom lenses 20 of the camera units 18a and 18b.

In the second embodiment, the light source 24 is disposed on the sideface of the first beam splitter 22. This light source may be disposedoutside the system to emit light, which is guided by an optical fiber tothe first beam splitter 22.

When optical axis deviations occur on the zoom lenses 20 of the secondembodiment, the correction signal generator 32 outputs the correctionsignals 33a and 33b to drive the moving mechanisms 2a and 2b tomechanically correct the optical axis deviations. The correction signals33a and 33b may be used to electrically move images displayed on thedisplay unit 14 to compensate for optical axis deviations.

The second embodiment can automatically correct deviations of opticalaxes of optical systems of camera units due to operation of the zoomlenses or changes in observing angles of an object. Therefore, goodimages are displayed on a display unit so that a viewer can always senseproper stereoscopic images.

FIG. 5 shows a stereoscopic television system according to the thirdembodiment of the invention.

As shown in the FIGURE, the stereoscopic television system of the thirdembodiment comprises a camera unit 40. In front of the camera unit 40,that is an object A that provides a right image beam 1₂ and a left imagebeam 1₁. The image light beams are made incident to right and leftincident slits 41a and 41b, respectively. The slits are formed on thefront face of the camera unit 40.

Facing the right incident slit 41a, there is a reflector 42 to reflectthe right image beam 1₂. The right image beam 1₂, reflected by thereflector 42, reaches an S-type polarizing plate 43. The beam passedthrough the S-type polarizing plate 43 becomes an S-type polarized beam1₄ that is made incident to a beam splitter 44.

Facing the left incident slit 41b, a First-type polarizing plate 45 isarranged. The left light beam passes through the First-type polarizingplate 45 to become a First-type polarized beam 1₅, which is madeincident to the beam splitter 44. Due to the beam splitter 44, thepolarized beam 1₄ and 1₅ that have passed through the Second-type andFirst-type polarizing plates 43 and 45 follow a common optical axis.

The left and right polarized beams 1₄ and 1₅ from the beam splitter 44are made incident to a polarization switch 46. The polarization switch46 is driven by a polarization switch driver 47 such that theSecond-type and First-type polarized beams are alternately passedthrough the switch 46.

The Second-type and First-type polarized beams alternately switched bythe polarization switch 46 are passed through a zoom lens 48 to formimages on a television camera 49. Therefore, on the television camera49, right images and left images are alternately displayed according tothe operation of the switch 46.

Switching timing of the polarization switch 46 is controlled by thepolarization switch driver 47 that is controlled by a controller 50 suchthat the timing is synchronized with a field rate of the televisioncamera 49. The television camera 49 transmits video signals of imagesfor left and right eyes alternately for every frame.

The video signals from the television camera 49 are sent to thecontroller 50, in which frequencies of the signals are up-converted.Then, the signals are sent to a monitor television unit 51 to displayimages. The images displayed on the monitor television unit 51 arepolarized by a polarization switch 52 disposed in front of the monitortelevision unit 51. A viewer 53 wears polarizing spectacles 54 to seeleft and right images with corresponding eyes to sense stereoscopicimages.

According to this stereoscopic television system, the right image beam1₂ and the left image beam 1₁ are passed through the polarizing plates43 and 45, beam splitter 44 and polarization switch 46, and madeincident to the single zoom lens 48. Therefore, compared to those casesof employing a plurality of optical systems such as zoom lenses, opticalaxis deviation due to zooming operation never occurs and, therefore, thedisplayed images never deviate from their correct positions in the thirdembodiment. As a result, good images are displayed and a viewer canalways sense proper stereoscopic images.

FIG. 6 shows a stereoscopic television system according to amodification of the third embodiment of the invention.

The modification has the same arrangement as the third embodiment fromthe object A to the Zoom lens 48.

First-type polarized beam and Second-type polarized beam from the zoomlens 48 are divided into First-type and Second-type beams by apolarizing beam splitter 55, and the beams are made incident to twovideo cameras 56 and 57, respectively. Video signals from the two videocameras 56 and 57 are passed through a controller 50 and alternatelyoutputted to a monitor television unit 51 at predetermine intervals,i.e., at switching timing of the polarization switch 46. Imagesdisplayed on the monitor television unit 51 are polarized by apolarization switch 52 disposed in front of the monitor television unit51. A viewer 53 wears polarizing spectacles 54 to see left and rightimages with his corresponding eyes to sense stereoscopic images.

As described in the above, according to the third embodiment of theinvention, right image beams and left image beams are made incident to asingle optical system such as a zoom lens and processed so that opticalaxis deviation due to zooming operation of the optical system neveroccurs, thus always providing proper stereoscopic images.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

What is claimed is:
 1. A stereoscopic television system employing aplurality of camera units, each unit having an optical system and animage pickup element to photograph and display images of an object, thedisplayed images being processed with stereoscopic image processingmeans to provide stereoscopic images, the system comprising:detectingmeans for receiving image signals based on the images photographed bythe camera units and correlatively comparing the image signals through aplurality of image information integrators and a relative deviationoperating unit; and correcting means for correcting the deviations ofimages according to the image deviation signals provided by thedetecting means.
 2. A stereoscopic television system according to claim1, wherein the correcting means comprises a plurality of optical axisdeviation operating units to avoid any optical axis deviation due tozooming operation.
 3. A stereoscopic television system employing aplurality of camera units, each having an optical system and an imagepickup element to photograph and display images of an object, thedisplayed images being processed with stereoscopic image processingmeans to provide stereoscopic images, the system comprising:detectingmeans comprising a plurality of image information integrators forreceiving image signals from the camera units and compressing the imagesignals from the camera units by integrating the image signals toprovide a distribution of light quantities of a predetermined direction,a correlative deviation operating unit for correlatively comparing theimage signals which have been subjected to the conversion of thedistribution of light quantities in the image information integratorsfor numerically calculating the deviations of the images in thepredetermined direction to detect numerical deviations of the images;and correcting means for correcting the deviation signals provided bythe detecting means.
 4. The system of claim 2, wherein a two-dimensionaldistribution of light quantities is converted into a one-dimensionaldistribution.
 5. A stereoscopic television system employing a pluralityof camera units each having an optical system and an image pickupelement to photograph and display images of an object, the displayedimage being processed with stereoscopic images processing means toprovide stereoscopic images, the system comprising:detecting meanscomprising a plurality of image information integrators to provide adistribution of light quantities of a predetermined direction, each ofwhich comprises:a monitor television unit for displaying an image basedon the image signals sent from corresponding one of the camera units; acylindrical lens for one-dimensionally integrating the image displayedon the monitor television unit; a plurality of image pickup elements forpicking up an image on the cylindrical lens, and a correlative deviationoperating unit for correlatively comparing the image signals which havebeen subjected to a conversion of the distribution of light quantitiesin the image information integrators and numerically calculating thedeviations of the images in the predetermined direction to detectnumerical deviations of the images; and correcting means for correctingthe deviation signals provided by the detecting means.
 6. A stereoscopictelevision system employing a plurality of camera units each having anoptical system and an image pickup element to photograph and displayimages of an object, the displayed images being processed withstereoscopic image processing means to provide stereoscopic images, thesystem comprising:detecting means comprising a plurality of imageinformation integrators for receiving the image signals from the cameraunits and compressing the image signals by integrating the imagesignals, to provide a distribution of light quantities of a verticaldirection, i.e., converting a two-dimensional distribution of lightquantities into the one-dimensional distribution of light quantities ofthe vertical direction; and correcting means for correcting the imagesprovided by the detecting means.
 7. A stereoscopic television system fordisplaying photographed images of an object, the displayed images beingprocessed with stereoscopic image processing means to providestereoscopic images, the system comprising:(a) a plurality ofphotographing means each having:an optical system; an image pickupelement; a first beam splitter disposed between the optical system andthe image pickup element; a second beam splitter disposed on the objectside of the optical system; a light source for omitting a referencebeam, which is made incident to the first beam splitter, reflected bythe first beam splitter, passed through the optical system and madeincident to the second beam splitter; and a light receiving element forreceiving the reference beam reflected by the second beam splitter; (b)arithmetic means for calculating deviations of the optical axis of therespective optical systems based on the reference beams received by thelight receiving elements, to provide deviation information; and (c)correcting means for correcting deviations of the optical axis of theoptical systems according to the deviation information provided by thearithmetic means.
 8. The stereoscopic television system according toclaim 6, wherein the arithmetic means comprises:a plurality ofarithmetic units for calculating deviations of positional signalsprovided by the light receiving elements from previously storedreference positions to output resultant deviation signals; and arelative deviation arithmetic unit for calculating a relative deviationof the optical axis of the camera units according to the deviationsignals provided by the arithmetic units, to output a relative deviationsignal as the deviation information.